Use Summation Notation
- $a + a r + a r ^ { 2 } + \ldots + a r ^ { 11 }$

Multiple Choice

Use Summation Notation
- $a + a r + a r ^ { 2 } + \ldots + a r ^ { 11 }$

A) $\sum _ { \mathrm { i } = 1 } ^ { 12 } a \mathrm { r } ^ { \mathrm { i } - 1 }$
B) $\sum _ { \mathrm { i } = 1 } ^ { 11 } a r ^ { \mathrm { i } }$
C) $\sum _ { \mathrm { i } = 1 } ^ { 11 } ( \mathrm { ar } ) ^ { \mathrm { i } }$
D) $\sum _ { \mathrm { i } = 1 } ^ { 11 } ( \mathrm { ar } ) ^ { \mathrm { i - 1}}$ Express the sum using summation notation. Use a lower limit of summation not necessarily 1 and k for the index of summation.